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Two minimal Tat translocases in Bacillus
Jan D H Jongbloed1, Ulrike Grieger, Haike Antelmann
1Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, Kerklaan 30, 9751 NN Haren, the Netherlands.
Molecular Microbiology
|November 24, 2004
Summary
The Tat protein transport machinery in Bacillus subtilis differs significantly from E. coli, utilizing minimal TatAC translocases instead of TatABC. These TatAC systems are specific for different twin-arginine preproteins.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- The Tat (twin-arginine translocation) system facilitates protein transport across membranes.
- In Escherichia coli and chloroplasts, TatABC proteins are essential for Tat machinery function.
- Gram-positive bacteria possess distinct Tat machinery components.
Purpose of the Study:
- To investigate the composition and function of the Tat machinery in Bacillus subtilis.
- To determine if Bacillus subtilis utilizes a TatABC or a modified Tat system.
- To understand the substrate specificity of identified Tat translocases.
Main Methods:
- Bacterial genetics and protein biochemistry techniques were employed.
- Mutational analysis was used to identify essential Tat components.
- In vivo and in vitro assays were performed to assess protein transport and complex formation.
Main Results:
- Bacillus subtilis Tat machinery comprises at least two minimal TatAC translocases, not TatABC.
- TatA proteins in B. subtilis appear to perform functions of both TatA and TatB from E. coli.
- Specific TatAC complexes (TatAdCd and TatAyCy) were shown to transport distinct twin-arginine preproteins (PhoD and YwbN).
Conclusions:
- The predominant Gram-positive bacterial Tat machinery is based on minimal TatAC translocases.
- This finding represents a significant divergence from the TatABC system found in E. coli and thylakoids.
- The study reveals substrate-specific TatAC translocases as a conserved mechanism in most Gram-positive bacteria.